Study on the rock physical mechanical properties evaluation of tight oil reservoir in Chang 7 member, Longdong area, Ordos Basin, China

The study aims to investigate the rock mechanical properties of the Chang 7 member tight oil reservoir in the Longdong region of the Ordos Basin, China, with the goal of enhancing the efficiency of oilfield development. Despite numerous contributions in the field of rock mechanics, challenges persist in reconciling experimental results with actual geological conditions and achieving comprehensive understanding of rock mechanical properties in tight oil reservoirs. To address this, a variety of experimental methods were employed to systematically assess the mechanical properties of the target reservoir. Rock density was measured using volumetric methods, tensile strength was evaluated through the Brazilian test, uniaxial and triaxial compression tests were conducted to assess rock mechanics properties, and dynamic elastic modulus and Poisson’s ratio were obtained via sonic velocity measurements. Furthermore, differential strain analysis and imaging log analysis were employed to determine the magnitude and direction of geostress. The results revealed that fine-grained sandstone exhibited higher rock density and relatively higher tensile strength, while muddy siltstone exhibited comparatively lower values in these aspects. Analysis of the influence of confining pressure on rock mechanics properties demonstrated a strong positive correlation between compressive strength and Young’s modulus with confining pressure, while Poisson’s ratio exhibited more irregular variations. Additionally, a mathematical relationship between dynamic and static rock mechanical parameters was established. Lastly, based on the characteristics of geostress, reliable foundations for optimizing hydraulic fracturing and wellbore layout were provided. This study has enriched and complemented the investigation of rock mechanical properties in tight reservoirs, offering vital parameters and theoretical support for the development of tight oil reservoirs. This bears significant importance in enhancing petroleum extraction efficiency and optimizing engineering design

Analysis of methods for quantifying yeast cell concentration in complex lignocellulosic fermentation processes

Cell mass and viability are tightly linked to the productivity of fermentation processes. In 2nd generation lignocellulose-based media quantitative measurement of cell concentration is challenging because of particles, auto-fluorescence, and intrinsic colour and turbidity of the media. We systematically evaluated several methods for quantifying total and viable yeast cell concentrations to validate their use in lignocellulosic media. Several automated cell counting systems and stain-based viability tests had very limited applicability in such samples. In contrast, manual cell enumeration in a hemocytometer, plating and enumeration of colony forming units, qPCR, and in situ\ufeff dielectric spectroscopy were further investigated. Parameter optimization to measurements in synthetic lignocellulosic media, which mimicked typical lignocellulosic fermentation conditions, resulted in statistically significant calibration models with good predictive capacity for these four methods. Manual enumeration of cells in a hemocytometer and of CFU were further validated for quantitative assessment of cell numbers in simultaneous saccharification and fermentation experiments on steam-exploded wheat straw. Furthermore, quantitative correlations could be established between these variables and in situ permittivity. In contrast, qPCR quantification suffered from inconsistent DNA extraction from the lignocellulosic slurries. Development of reliable and validated cell quantification methods and understanding their strengths and limitations in lignocellulosic contexts, will enable further development, optimization, and control of lignocellulose-based fermentation processes

3DMIT: 3D Multi-modal Instruction Tuning for Scene Understanding

The remarkable potential of multi-modal large language models (MLLMs) in comprehending both vision and language information has been widely acknowledged. However, the scarcity of 3D scenes-language pairs in comparison to their 2D counterparts, coupled with the inadequacy of existing approaches in understanding of 3D scenes by LLMs, poses a significant challenge. In response, we collect and construct an extensive dataset comprising 75K instruction-response pairs tailored for 3D scenes. This dataset addresses tasks related to 3D VQA, 3D grounding, and 3D conversation. To further enhance the integration of 3D spatial information into LLMs, we introduce a novel and efficient prompt tuning paradigm, 3DMIT. This paradigm eliminates the alignment stage between 3D scenes and language and extends the instruction prompt with the 3D modality information including the entire scene and segmented objects. We evaluate the effectiveness of our method across diverse tasks in the 3D scene domain and find that our approach serves as a strategic means to enrich LLMs' comprehension of the 3D world. Our code is available at https://github.com/staymylove/3DMIT.Comment: 9 pages, 5 figure

Learning by Analogy: Reliable Supervision from Transformations for Unsupervised Optical Flow Estimation

Unsupervised learning of optical flow, which leverages the supervision from view synthesis, has emerged as a promising alternative to supervised methods. However, the objective of unsupervised learning is likely to be unreliable in challenging scenes. In this work, we present a framework to use more reliable supervision from transformations. It simply twists the general unsupervised learning pipeline by running another forward pass with transformed data from augmentation, along with using transformed predictions of original data as the self-supervision signal. Besides, we further introduce a lightweight network with multiple frames by a highly-shared flow decoder. Our method consistently gets a leap of performance on several benchmarks with the best accuracy among deep unsupervised methods. Also, our method achieves competitive results to recent fully supervised methods while with much fewer parameters.Comment: Accepted to CVPR 2020, https://github.com/lliuz/ARFlo

Analytical modeling of gas production rate in tight channel sand formation and optimization of artificial fracture

Permeability variation in tight channel sand formation makes an important role in gas production. Based on the features of channel sand formation, a mathematical model has been established considering anisotropy of permeability. The analytical solutions were derived for productivity of both vertical wells and vertically fractured wells. Simulation results show that, gas production rate of anisotropic channel sand formation is less than that of isotropic formation. For vertically fractured well, artificial fracture direction, drainage radius, permeability ratio and fracture half-length have considerable influence on production rate. The optimum fracture direction should be deviated less than π/8 from the maximum permeability direction (or the channel direction). In addition, the analytical model was verified by in situ measured data. The research provides theoretical basis for the development of tight channel sand gas reservoirs

Mechanical Deformation Behavior of Nonpolar GaN Thick Films by Berkovich Nanoindentation

In this study, the deformation mechanisms of nonpolar GaN thick films grown on m-sapphire by hydride vapor phase epitaxy (HVPE) are investigated using nanoindentation with a Berkovich indenter, cathodoluminescence (CL), and Raman microscopy. Results show that nonpolar GaN is more susceptible to plastic deformation and has lower hardness thanc-plane GaN. After indentation, lateral cracks emerge on the nonpolar GaN surface and preferentially propagate parallel to the orientation due to anisotropic defect-related stresses. Moreover, the quenching of CL luminescence can be observed to extend exclusively out from the center of the indentations along the orientation, a trend which is consistent with the evolution of cracks. The recrystallization process happens in the indented regions for the load of 500 mN. Raman area mapping indicates that the distribution of strain field coincides well with the profile of defect-expanded dark regions, while the enhanced compressive stress mainly concentrates in the facets of the indentation

Bioprocess development for biochemical conversion of lignocellulose

Due to its low environmental impact and high maturity of the fuel ethanol market, lignocellulosic ethanol is a promising option for reducing the carbon footprint in the transport sector. The characteristics of lignocellulosic feedstocks, such as varied sugar composition, low sugar density, low solubility, recalcitrance to enzymatic degradation, and inhibitors formed during thermochemical pretreatment, have so far limited the production process, and costs for conversion of lignocellulosic materials to ethanol are still high. In this thesis, I describe the development of a bioconversion process that pushes the limits of simultaneous saccharification and co-fermentation (SSCF) to achieve higher ethanol titre, yield and productivity on lignocellulosic feedstocks. I propose an integrated fed-batch strategy, Multi-Feed SSCF, including feeds of substrates, enzymes and adapted cells to tackle the technical challenges in operating a SSCF process at high substrate loadings. Using insights from experiments and a model-based feeding design, lignocellulose saccharification and fermentation at water insoluble solids (WIS) levels greater than 20% (w/w) was achieved. The multi-feed SSCF concept and model-aided substrate feeding design allowed rapid, reproducible, and scalable bioconversion of lignocellulose, as proven on several lignocellulosic feedstocks in both laboratory and demonstration scales. Ethanol production above 50 g/L in SSCF processes was found to be severely inhibited by the combined effects of ethanol, lignocellulose-derived inhibitors, and higher than standard cultivation temperature (35\ub0C). Cell viability and fermentation improved significantly in a multi-feed SSCF process with a step change in temperature from 35 to 30\ub0C, compared to operation at 35\ub0C throughout. However, introducing the Erg3Tyr185 point mutation which has been reported to render thermotolerance in yeast, did not offer any significant improvement. Cell concentrations were determined by counting in a hemocytometer and colony forming unit assay. Their accuracy and reproducibility in lignocellulosic media, were verified by Design-of-Experiment-based calibration. Applic-ability of real time qPCR and dielectric spectroscopy as potential cell quantification methods was also investigated. With multi-feed of solid substrates, enzyme preparations, and adapted cells, the SSCF process produced > 60 g/L ethanol within 120 h, equivalent to 70% of the theoretical yield of the total sugar input, and 90% of the consumed sugar. The systematic optimisation reported in this work represents a robust and reproducible routine for developing lignocellulose-based processes. It could inspire continuous development of alternative strategies to current fossil-based chemical/fuel processes